Shoe insole with layered partial perforation

ABSTRACT

A shoe insole which, within a shoe, combines shock cushioning, heat dissipating, moisture-removing, and low-frictioning contact with the underside of the foot. The insole preferably includes two adhesively bonded layers. The lower layer is a shock-cushioning layer which includes plural, elongate, through-bore perforations that are distributed in a grid fashion throughout the layer, with each perforation extending completely through the thickness of this lower layer, and opening to opposite (upper and lower) faces in the lower layer. The upper layer is a continuous, non-perforated moisture-wicking, low-frictioning, fabric layer which extends across and spans the upper, otherwise open ends of the perforations.

INTRODUCTION

[0001] This invention relates to a shock-absorbing, cushioning insole for a shoe, and more particularly to such an insole which, in addition to possessing a structure capable of furnishing superior shock-absorbing performance, is also specially constructed to dissipate heat very efficiently and effectively.

[0002] The environment inside the usual worn shoe is, generally speaking, a very warm environment. With regard to shoes that are designed for, and that work to promote, vigorous activity such as exercise walking and running, it is common for wearers to seek, or if necessary to equip, shoes with special shock-absorbing cushioning insoles (or the like) which significantly enhance the wearer's/user's comfort. Other activities, including various therapeutic, walking-related activities, which do not necessarily entail strenuous and/or pounding foot behavior, are also often made more comfortable, acceptable and effective where a cushioning insole, etc., structure, like that just above mentioned, is present in a shoe.

[0003] A sometimes encountered side effect, however, to the presence of such cushioning structure in a shoe is an accompanying increased build-up of heat within the shoe, resulting from additional heat that becomes generated therein because of the active “working” which takes place within the included shock-absorbing cushioning material.

[0004] There is thus a strong interest in many instances to provide a shoe, for use in activity circumstances like those generally mentioned above, with an effective shock-absorbing cushioning capability which is also characterized by robust heat-removal that can deal definitively with potential additional heat build-up which may occur as a consequence of active and efficient cushioning and shock absorption.

[0005] In this setting, the present invention proposes a unique and strikingly effective shoe insole structure which features a pair of (upper and lower) preferably bonded layers, the lower one of which is formed of an acceleration-rate-sensitive, viscoelastic, cushioning and shock-absorbing material, and the upper one of which is formed of an overlayer of a suitable, low-friction, moisture-wicking fabric material.

[0006] The upper layer of fabric material, which possesses significant low-frictioning and moisture-wicking properties, is formed as a continuous (unbroken) expanse. The lower layer of cushioning material, in accordance with the present invention, is characterized with a unique distribution of through-layer (from top to bottom) perforations that are distributed as clear, though-bore-like, preferably (though not at all necessarily) cylindrical passages that open to both faces (upper and lower) in the cushioning material. Significantly, however, no through-bore perforations extend through the overlayer fabric material, which material completely spans (unperforated) each of the otherwise open upper-surface ends of the through-bore perforations in the cushioning material.

[0007] This special, perforate-single-layer, fabric-bridged insole structure offers a robust cooling behavior which remarkably divorces the high-performance, high-capability cushioning and shock-absorbing performance of a material, like the preferred acceleration-rate-sensitive viscoelastic material mentioned above, from the attendant heat build-up side effects which can be generated.

[0008] These and other features and advantages that are attained by the present invention will become more fully apparent as the description which now follows is read in conjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS

[0009]FIG. 1 is an isolated top plan view of a shoe insole constructed in accordance with a preferred embodiment of the present invention. Portions of a fabric overlayer are broken away in order to reveal underlying details of construction.

[0010]FIG. 2 is an enlarged, fragmentary, cross-sectional view taken generally along the line 2-2 in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

[0011] Turning now to both drawing figures, indicated generally at 10 is a cushioning, heat-dissipating shoe insole which is constructed fully in accordance with a preferred and best mode embodiment of the present invention. Insole 10 is illustrated in an isolated condition herein, separated from other shoe structure simply for the sake of convenience in picturing and describing it. It will be understood, of course, that this insole structure may either indeed be a “stand alone” structure which is selectibly insertable into an independent shoe, or it may be a structure which is built as an integral part originally of a shoe. The upper side, or surface, of insole 10 faces the viewer in FIG. 1, and is disposed at the upper side of FIG. 2.

[0012] Preferably, insole 10 is a two-layer structure, including a lower, shock-absorbing, impact-cushioning layer 12, and an upper, moisture-wicking, low-friction fabric layer 14 which is bonded as an unbroken, uninterrupted overlayer on the upper surface of layer 12.

[0013] While different very specific cushioning, etc. materials may be chosen for layer 12, most preferably all such selections lie in the category of an acceleration-rate-sensitive, viscoelastic material. A very satisfactory, and currently most preferred, material choice for layer 12 is the material which is identified as PORON® 400 Performance Urethane, Series 90, Formation #94. This particular material is manufactured by Rogers Corporation in Woodstock, Conn. A preferred thickness T for this layer lies in the range of about ⅛-¼-inches. A thickness of about {fraction (3/16)}-inches has been found to be a very good choice within this range.

[0014] According to the invention, layer 12 is perforated by a uniform, overall grid pattern of plural, generally cylindrical, through-bore passages 16, each of which opens to both the upper and the lower surfaces (12 a, 12 b, respectively) of layer 12. Each of these passages has an axis, such as axes 16 a, of cylindrical symmetry that extends as shown between the upper and lower faces of layer 12. While different specific perforation dimensions and center-to-center spacings of perforations, may be selected, in insole 10, perforations 16 have cross-sectional diameters D each of about 0.05-inches, and center-to-center spacings S of about 0.25-inches. As was mentioned earlier, non-cylindrical perforations may be used if desired.

[0015] Fabric overlayer 14 is preferably formed of a woven-fibre fabric material, such as that known as HEATHERSTONE®, made by Lee Fashion Fabrics, Inc. in Gloversville, N.Y. This material possesses excellent moisture-wicking and low-frictioning properties. Fabric layer 14 herein has a thickness preferably of about {fraction (1/64)}-inches.

[0016] Layer 14 is suitably bonded, as by an appropriate adhesive 18, to the upper surface of layer 12, and completely over-spans the otherwise open upper ends of perforations 16. Significantly, perforations 16 do not have upper extensions through the fabric layer. Such extensions would inevitably result in exposed fabric-thread ends which, among other undesirable things, would be subject to fraying, and could result in tattering and disintegration of the fabric overlayer. In addition, perforation extensions through the fabric layer will significantly degrade the overlayer's moisture-wicking capabilities by the fact that there would be introduced to it numerous and widely distributed discontinuities in the preferable, desirable, unbroken continuity expanse for moisture wicking which occurs where such extensions do not exist. Still another potentially significant drawback to perforations in the fabric material, stemming from tattering and fraying, is that the exposed, scattered ends of broken fabric threads could appreciably reduce the otherwise desirable low-frictioning characteristic of the fabric.

[0017] Experience with the insole structure of this invention, now fully described, is that it furnishes both very significant cushioning and shock-absorbing performance, while at the same time offering significant heat dissipation and moisture removal. Such very appreciable heat-removal performance is one that (a) not only deals robustly with the expected, normal heat build-up in a working shoe, but also (b) significantly obviates the additional heat build-up which accompanies, as an unwelcome side effect, the energetic working shock-absorbing and cushioning behavior definitively called upon, and desired from, the viscoelastic cushioning layer.

[0018] Accordingly, while a preferred embodiment of the invention has been illustrated and described herein, it is appreciated that variations and modifications may be made without departing form the spirit of the invention. 

We claim:
 1. A shoe insole comprising a cushioning underlayer having upper and lower faces which constitute opposite faces in this layer, plural perforations extending through, and opening to opposite faces of, said cushioning layer, and an overlayer expanse of low-frictioning, moisture-wicking, fabric material distributed as a continuum over the upper face of said cushioning layer, and effectively completely spanning said perforations where they open to and are exposed at the upper face of said cushioning layer.
 2. The insole of claim 1, wherein said cushioning layer is formed of an acceleration-rate-sensitive, viscoelastic material.
 3. The insole of claim 1, wherein said cushioning layer and said fabric overlayer are joined to one another through adhesive bonding.
 4. The insole of claim 1, wherein said perforations are distributed in a uniform grid pattern over and through said cushioning layer.
 5. The insole of claim 4, wherein said perforations are generally cylindrical in nature, with their respective axes of cylindrical symmetry extending through said cushioning layer between its upper and lower faces. 